I have been happy with the 525 pitch chain as comes stock. I can't see the need to change to 520 pitch for the sake of a few dollars and grams in weight. The 525 is strong, doesn't stretch too quickly and easier on sprockets. I am happy with the RK brand and haven't tried any other to comment on any differences.

FRONT SPROCKET - JT brand steel 525 pitch, 14/15 tooth

The steel sprockets are robust and last well if looked after. I change from 14 tooth to 15 tooth depending on the requirements of the ride

REAR SPROCKET - JT brand steel 525 pitch 41 tooth

I haven't had the need to change from the stock size rear sprocket, preferring to change the front sprocket to change gearing if I want. The steel sprockets are long wearing and strong.

When changing to a smaller front sprocket, the stock OEM is too large and will hit on the chain. An easy solution is to removed the rubber damper which does nothing anyway, and grind the retainer down to a smaller diameter. Refit the retainer without the damper and check the chain is not hitting it. I recommend blue loctite on the retaining bolts. Photo compliments of ER07S-2.

COUNTERSHAFT SEAL RETAINER

The countershaft seal retainer will stop the countershaft seal popping out and causing a major bleed of oil from the engine on earlier models not fitted with this. My seal is still original and has never been out but I put one of these on for insurance. Suzuki obviously realised this and it now comes stock on all new models since 2012